AI doesn't have to be evil to destroy humanity.

If AI has a goal, and humanity just happens to be in the way

If AI has a goal, and humanity just happens to be in the way, it will destroy humanity as a matter of course without even thinking about it. No hard feelings. It's just like if we're building a road, and an anthill happens to be in the way, we don't hate ants. We're just building a road. And so goodbye anthill.